In loading or unloading a ship, it often becomes necessary to load or partially unload the cargo such that the ship is trimmed bow up or down as much as 5 degrees. This is the calm water condition of the ship and at 5 degrees of trim results in a bow to stern difference in elevation of over 8 feet per 100 feet of ship length. Land-based installations routinely use a duplex compressor arrangement where one double shaft motor drives two compressors. However, the roll of a ship requires that such an arrangement be oriented in the direction of the keel of the ship and this creates oil level problems due to the trim of the ship if a conventional system of cross-connecting duplex compressors is used which employs interconnecting tubes above and below the oil level in the crankcases. More specifically, typical large 8-cylinder compressors duplexed and driven by a motor located between them would have the oil pump suction tubes placed about 9 feet apart. Depending upon the trim of the ship, the "low" compressor could have too high of an oil level while the "high" compressor could have too low of an oil level if a conventional system of cross-connecting duplex compressors is used. The "high" compressor would run out of oil, causing the low oil pressure safety switch to stop the motor. Since continuous air conditioning plant operational capability is essential, this situation would be intolerable. The problem cannot be cured by raising the oil level in the compressors since the "low" compressor would have an intolerably excessive oil level long before an adequate level could be established in the "high" compressor.